Spring assembly and manufacturing method therefor

ABSTRACT

According to one embodiment, a spring assembly includes: a substrate; a coil spring having an end turn portion fixed to the substrate; an inner wall provided at an inner peripheral side of the coil spring; and an outer wall provided at an outer peripheral side of the coil spring, wherein one of the inner wall and the outer wall forms a spring fixing wall configured to prevent the end turn portion of the coil spring from coming off in an axial direction of the coil spring, and wherein the other of the inner wall and the outer wall forms a support wall configured to prevent the end turn portion of the coil spring from moving in a radial direction of the coil spring.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priorities from Japanese Patent Application No.2009-145878 filed on Jun. 18, 2009, Japanese Patent Application No.2009-276074 filed on Dec. 4, 2009, and Japanese Patent Application No.2010-117137 filed on May 21, 2010, the entire contents of which areincorporated herein by reference.

BACKGROUND

1. Field of the Invention

An aspect of the present invention relates to a spring assembly to beused as, for example, a return spring for a multi-plate clutch piston ina clutch mechanism of an automatic transmission of an automobile.

2. Description of the Related Art

JP-2005-024003-A discloses a spring assembly including two annularplates and plural coil springs interposed between the two annularplates. In the spring assembly, an end turn portion (end portion) of thecoil spring is inserted into a cylindrical projecting portion extendingfrom each annular plate, and then a distal opening edge of thecylindrical projecting portion is flared to stake (fix) the end turnportion of the coil spring to the cylindrical projecting portion of theannular plate.

In the spring assembly, when a large axial tensile force acts on thecoil spring, the end turn portion of the coil spring may be expanded toclimb over the distal opening edge of the cylindrical projectingportion, and the coil spring may come off the annular plate.

In a spring assembly disclosed in JP-UM-S61-112139-A, a coil spring hasan end turn portion broadened in a radial direction as compared with asecond-stage (or higher-stage) turn. For example, the end turn portionof the coil spring is inserted into a cylindrical boss extended from asubstrate, and a stepped cover is attached onto the substrate, therebysandwiching the end turn portion of the coil spring broadened in theradial direction by the stepped cover and the substrate in an axialdirection.

In the spring assembly of JP-UM-S61-112139-A, the end turn portion ofthe coil spring may not come off the substrate. However, since the endturn portion of the coil spring is broadened in the radial direction andthe stepped cover is provided in addition to the substrate and coilspring, the manufacturing process is cumbersome and complicated.

SUMMARY

One of objects of the present invention is to provide a spring assemblyto be easily processed and manufactured while securely fixing a coilspring to a substrate.

According to a first aspect of the present invention, there is provideda spring assembly including: a substrate; a coil spring having an endturn portion fixed to the substrate;

an inner wall provided at an inner peripheral side of the coil spring;and an outer wall provided at an outer peripheral side of the coilspring, wherein one of the inner wall and the outer wall forms a springfixing wall configured to prevent the end turn portion of the coilspring from coming off in an axial direction of the coil spring, andwherein the other of the inner wall and the outer wall forms a supportwall configured to prevent the end turn portion of the coil spring frommoving in a radial direction of the coil spring.

According to a second aspect of the present invention, there may beprovided the spring assembly, wherein the inner wall extends from thesubstrate along the inner peripheral side of the coil spring, andwherein the outer wall extends from the substrate along the outerperipheral side of the coil spring.

According to a third aspect of the present invention, there may beprovided the spring assembly, wherein the inner wall or the outer wallforming the support wall is formed by half blanking to the substrate.

According to a fourth aspect of the present invention, there may beprovided the spring assembly, wherein the inner wall or the outer wallforming the support wall is formed by cutting and bending up thesubstrate.

According to a fifth aspect of the present invention, there may beprovided the spring assembly, wherein the inner wall or the outer wallforming the spring fixing wall is formed as a cylindrical wall extendingfrom the substrate, wherein a distal opening edge of the cylindricalwall is broadened or narrowed in diameter to stake the end turn portionof the coil spring to the cylindrical wall of the substrate, wherein anextension amount of the spring fixing wall from the substrate is setlarger than a radius of a wire rod forming the coil spring, wherein aninterval between a distal end of the spring fixing wall and a distal endof the support wall after being staked is smaller than a diameter of thewire rod, and wherein a gap is formed between the outer wall or innerwall forming the support wall and the end turn portion of the coilspring.

According to a sixth aspect of the present invention, there may beprovided the spring assembly, wherein the inner wall or the outer wallforming the spring fixing wall is formed as a cylindrical wall extendingfrom the substrate, wherein a distal opening edge of the cylindricalwall is broadened or narrowed in diameter to stake the end turn portionof the coil spring to the cylindrical wall of the substrate, and whereinthe outer wall or inner wall forming the support wall is in contact withthe end turn portion of the coil spring.

According to a seventh aspect of the present invention, there may beprovided a method for manufacturing the spring assembly, the methodincluding: coaxially arranging the end turn portion of the coil springto the cylindrical wall of the substrate; and broadening or narrowingthe distal opening edge of the cylindrical wall in diameter to form thecylindrical wall into the spring fixing wall while bringing the end turnportion of the coil spring into contact with the outer wall or innerwall forming the support wall.

According to an eighth aspect of the present invention, there may beprovided the spring assembly, wherein the coil spring is provided as aninner coil spring, wherein an outer coil spring is arranged outside theinner coil spring, and wherein an end turn portion of the outer coilspring is narrowed in diameter to form the support wall.

According to a ninth aspect of the present invention, there may beprovided the spring assembly, wherein the end turn portion of the innercoil spring is also narrowed in diameter so that an inner diameter ofthe end turn portion of the outer coil spring is smaller than an outerdiameter of a second-stage turn of the inner coil spring.

According to a tenth aspect of the present invention, there may beprovided the spring assembly, wherein a convex portion protruding fromthe substrate is formed at the outer peripheral side of the end turnportion of the outer coil spring.

According to an eleventh aspect of the present invention, there may beprovided the spring assembly, wherein the coil spring is provided as anouter coil spring, wherein an inner coil spring is arranged inside theouter coil spring, and wherein an end turn portion of the inner coilspring is broadened in diameter to form the support wall.

According to a twelfth aspect of the present invention, there may beprovided the spring assembly, wherein the end turn portion of the outercoil spring is also broadened in diameter so that an outer diameter ofthe end turn portion of the inner coil spring is larger than an innerdiameter of a second-stage turn of the outer coil spring.

According to the first aspect of the present invention, the end turnportion of the coil spring is prevented from coming off in the axialdirection and from moving in the radial direction by simply providingthe inner wall and the outer wall, thereby securely fixing the coilspring to the substrate.

According to the second aspect of the present invention, the inner walland the outer wall extended from the substrate prevent the end turnportion of the coil spring from coming off in the axial direction andfrom moving in the radial direction, without special processing for thecoil spring or additional components, thereby simplifying the processingand the manufacturing.

According to the third aspect of the present invention, since the innerwall or the outer wall forming the support wall formed by half blankingfunctions also as a reinforce rib for the substrate, the strength of,the substrate is improved.

According to the fourth aspect of the present invention, in a case wherethe spring assembly is used as a return spring for a multi-plate clutchpiston in a clutch mechanism of an automatic transmission of anautomobile, when a lubricating oil is supplied to the part where thecoil spring is disposed, since a cutout hole opened in the substratefunctions as an oil-drain hole, the fluidity of the lubricating oil isimproved. Moreover, depending on the use, the cutout hole may functionas a water-drain hole.

According to the fifth aspect of the present invention, since a gap isformed between the outer wall or inner wall forming the support wall andthe end turn portion of the coil spring after staking, the support wallmay not interfere with a second-stage turn of the coil spring, and thecharacteristics of the coil spring may not fluctuate due to theexistence of the support wall. Moreover, even when the gap is formed,since the interval between the distal end of the support wall and thedistal end of the spring fixing wall after staking is smaller than thediameter of the wire rod forming the coil spring, the coil spring isreliably prevented from coming off the spring fixing wall.

According to the sixth aspect of the present invention, since the outerwall or inner wall forming the support wall contacts the end turnportion of the coil spring, the end turn portion of the coil spring issecurely supported without rattling.

According to the seventh aspect of the present invention, the supportwall prevents the radial movement of the end turn portion of the coilspring during the staking operation, so that the staking operation isuniformly performed and the rigidity is improved.

According to the eighth aspect of the present invention, in theconfiguration where an outer coil spring is arranged outside an innercoil spring, a fixing wall preventing the inner coil spring from axiallycoming off or a support wall preventing the inner coil spring fromradially moving can be formed by only narrowing the end turn portion ofthe outer coil spring in diameter.

According to the ninth aspect of the present invention, the outer coilspring is prevented from axially coming off by the second-stage turn ofthe inner coil spring.

According to the tenth aspect of the present invention, the convexportion protruding from the substrate prevents the radial movement ofthe outer coil spring, thereby enhancing the structural rigiditythereof, and preventing buckle of the outer coil spring.

According to the eleventh aspect of the present invention, in theconfiguration where an inner coil spring is arranged inside an outercoil spring, a fixing wall preventing the outer coil spring from axiallycoming off or a support wall preventing the outer coil spring fromradially moving can be formed by only broadening the end turn portion ofthe inner coil spring in diameter.

According to the twelfth aspect of the present invention, the inner coilspring is prevented from axially coming off by the second-stage turn ofthe outer coil spring.

According to the present invention, the end turn portion of a coilspring is prevented from coming off in the axial direction and frommoving in the radial direction by simply providing an inner wall and anouter wall, thereby securely fixing the coil spring to the substratewith the simple processing and the manufacturing.

DRAWINGS

FIG. 1 is an exploded perspective view of a spring assembly according toan embodiment, when the spring assembly is used as a return spring for amulti-plate clutch piston in a clutch mechanism of an automatictransmission of an automobile.

FIGS. 2A to 2C illustrate a fixing (staking) configuration of a coilspring and a substrate in a spring assembly according to a comparisonexample.

FIGS. 3A to 3D illustrate a fixing (staking) configuration of a coilspring and a substrate in a spring assembly according to a firstembodiment.

FIGS. 4A and 4B illustrate another fixing (staking) configuration in thespring assembly according to the first embodiment.

FIGS. 5A to 5D illustrate a spring assembly according to a secondembodiment, FIG. 5A and FIG. 5C illustrating respective examples, FIG.5B showing a part of FIG. 5A, FIG. 5D showing a part of FIG. 5C.

FIG. 6 illustrates the spring assembly according to a modification ofthe second embodiment.

FIG. 7 illustrates a spring assembly according to another modificationof the second embodiment.

FIG. 8A illustrates a spring assembly according to a third embodiment,and FIG. 8B illustrates a spring assembly according to a modification ofthe third embodiment.

FIGS. 9A and 9B illustrate example configurations for preventing thenon-fixed coil spring from coming off in the axial direction.

FIGS. 10A and 10B illustrate other example configurations for preventingthe non-fixed coil spring from coming off in the axial direction.

FIG. 11A illustrates a state where a free end shown in. FIG. 9B isbrought into contact with the counterpart member, and 11B illustrates astate where a free end shown in FIG. 10B is brought into contact withthe counter part member.

FIGS. 12A to 12E illustrate other fixing configurations of a coil springand a substrate.

FIGS. 13A to 13C illustrate still other fixing configurations of a coilspring and a substrate.

DETAILED DESCRIPTION

Hereinafter, spring assemblies according to embodiments will bedescribed with reference to the drawings. In the embodiments, the springassembly is exemplified as a return spring for a multi-plate clutchpiston in a clutch mechanism of an automatic transmission of anautomobile. However, the spring assemblies according to the embodimentsare not limited thereto and may be applied to the other purpose.

FIG. 1 is an exploded perspective view of a spring assembly according toan embodiment, when the spring assembly is used as a return spring for amulti-plate clutch piston in a clutch mechanism of an automatictransmission of an automobile.

For example, the spring assembly includes a pair of annular-shapedsubstrates 1 and plural coil springs 2. Each coil spring 2 has end turnportions 2 a at both ends thereof, and the end turn portions 2 a arefixed to each substrate 1 with given intervals. In the embodiment, theend turn portion 2 a of the coil spring 2 is fixed (staked) to thesubstrate 1 so as to create a friction fit therebetween. The substrate 1may be formed by connecting plural segmented substrate pieces into anannular shape.

FIGS. 2A to 2C illustrate a fixing (staking) configuration of a coilspring and a substrate in a spring assembly according to a comparisonexample.

For example, a cylindrical wall 11 is formed to extend from thesubstrate 1, and the end turn portion 2 a of the coil spring 2 is fittedwith this cylindrical wall 11 (FIG. 2A), and a distal opening edge ofthe cylindrical wall 11 is flared (broadened in diameter), therebyfixing (staking) the end turn portion 2 a (FIG. 2B).

When an axial tensile force acts on the coil spring 2 thus fixed(staked) to the substrate 1, as shown FIG. 2C, the end turn portion 2 amay be expanded in the radial direction to climb over the distal openingedge of the cylindrical wall 11 and may come off in the axial direction.

[First Embodiment]

FIGS. 3A to 3D illustrate a fixing (staking) configuration of a coilspring and a substrate in a spring assembly according to a firstembodiment.

The spring assembly has the following configuration to prevent the endturn portion 2 a from coming off.

That is, an inner wall 11 and an outer wall 12 are formed on thesubstrate 1. The inner wall 11 is extended to be along with an innerperipheral side of the coil spring 2, and the outer wall 12 is extendedto be along with an outer peripheral side of the coil spring 2. Theinner wall 11 functions as a spring fixing wall 11 that prevents the endturn portion 2 a of the coil spring 2 from coming off in the axialdirection, and the outer wall 12 functions as a support wall 12 thatprevents the end turn portion 2 a of the coil spring 2 from moving inthe radial direction.

A cylindrical wall 11 (to be processed into the spring fixing wall 11through staking) is extended almost perpendicularly from the substrate1. This spring fixing wall 11 is formed by, for example, burring.Moreover, the support wall 12 is formed by half blanking to thesubstrate 1. When the support wall 12 is formed by half blanking, nocutout hole is formed in the substrate 1, thereby maintaining rigidityof the substrate 1. Further, when the support wall 12 is formed by halfblanking, the support wall 12 functions also as a reinforce rib for thesubstrate 1, thereby improving rigidity of the substrate 1.

The coil spring 2 is fixed to the substrate 1 by the followingprocedure. That is, the end turn portion 2 a of the coil spring 2 isfitted with the cylindrical wall 11 (FIG. 3A). At this time, the supportwall 12 is positioned at the outer peripheral side of the end turnportion 2 a. In this condition, a distal opening edge of the cylindricalwall 11 is flared so that the end turn portion 2 a of the coil spring 2is fixed (staked) to the substrate 1 (FIG. 3B). At this time, the endturn portion 2 a of the coil spring 2 and the support wall 12 may beseparated with a gap D (FIG. 3C), or may be brought into contact witheach other (FIG. 3D).

As shown in FIG. 3C, when the gap D is formed between the end turnportion 2 a of the coil spring 2 and the support wall 12, the supportwall 12 may not interfere with a second-stage turn of the coil spring 2,and the characteristics of the coil spring 2 may not fluctuate due tothe existence of the support wall 12. The extension amount H of thesupport wall 12 from the substrate 1 may be set larger than a radius Rof a wire rod forming the coil spring 2 (H>R), and the interval Lbetween the distal end of the spring fixing wall 11 and the distal endof the support wall 12 after being fixed (staked) may be set smallerthan a diameter 2R of the wire rod (L<2R). By such a configuration, evenwhen the gap D is formed, the coil spring 2 is reliably prevented fromcoming off the spring fixing wall 11.

When the end turn portion 2 a of the coil spring 2 and the support wall12 are brought into contact with each other as shown in FIG. 3D, a gapmay be formed between the end turn portion 2 a and the support wall 12before starting the staking operation, and the end turn portion 2 a ofthe coil spring 2 may be radially expanded to contact the support wall12 as a result of the staking operation. In this way, the support wall12 prevents the radial movement of the end turn portion 2 a of the coilspring 2 during the staking operation, so that the staking operation isuniformly performed and the rigidity is improved. Since the support wall12 contacts the end turn portion 2 a of the coil spring 2, the end turnportion 2 a is securely supported without rattling.

The support wall 12 may be formed by cutting and bending up thesubstrate 1 as shown in FIGS. 4A and 4B. In a case where the substrate 1is cut and bent up to form the support wall 12, a cutout hole 12 a isopened in the substrate 1. This cutout hole 12 a can be used as anoil-drain or water-drain hole. For example, in a case where the springassembly is used as a return spring for a multi-plate clutch piston in aclutch mechanism of an automatic transmission of an automobile, when alubricating oil is supplied to the part where the coil spring 2 isdisposed, the lubricating oil can be discharged through the cutout hole12 a, thereby improving fluidity of the lubricating oil.

FIG. 4A shows a state before flaring the distal opening edge of thecylindrical wall 11, and FIG. 4B shows a state after flaring the distalopening edge to fix (stake) the end turn portion 2 a of the coil spring2.

The present invention is not limited to the above embodiment, and forexample, the outer wall and inner wall formed on the substrate may beinterchanged so that the outer wall functions as a spring fixing walland the inner wall functions as a support wall.

[Second Embodiment]

Next, a second embodiment will be described.

In a spring assembly according to the present embodiment, plural coilsprings are coaxially arranged to increase the spring force against thesubstrate.

FIGS. 5A to 5D illustrate a spring assembly according to the secondembodiment, FIG. 5A and FIG. 5C illustrating respective examples, FIG.5B showing a part of FIG. 5A, FIG. 5D showing a part of FIG. 5C.

As shown in FIG. 5A, an inner coil spring 2 and an outer coil spring 20are coaxially arranged on the substrate 1. The outer coil spring 20arranged outside the inner coil spring 2 has an end turn portion 20 anarrowed in diameter, and the end turn portion 20 a functions as asupport wall for the inner coil spring 2. That is, by narrowing the endturn portion 20 a of the outer coil spring 20 in diameter, the end turnportion 20 a closely approach or contact the end turn portion 2 a of theinner coil spring 2 from outside. Thus, the end turn portion 2 a of theinner coil spring 2 is prevented from moving in the radial direction bythe end turn portion 20 a of the outer coil spring 20.

In addition, as in the first embodiment, a spring fixing wall 11 isformed to extend from the substrate 1 at the inner peripheral side ofthe inner coil spring 2.

As shown in FIG. 5B, a radius R1 of a wire rod forming the outer coilspring 20 may be set larger than a radius R2 of a wire rod forming theinner coil spring 2 (R1>R2). In this case, when being attempted to comeoff, the end turn portion 2 a of the inner coil spring 2 contacts theend turn portion 20 a of the outer coil spring 20 and is prevented fromcoming off in the axial direction. That is, the outer coil spring 20functions as the spring fixing wall. When the outer coil spring 20functions as the spring fixing wall preventing the inner coil spring 2from coming off, the cylindrical wall 11 of the substrate 1 is notnecessary to function as the spring fixing wall and only necessary tofunction as the support wall preventing the inner coil spring 2 frommoving in the radial direction. Therefore, it is not necessary to fixthe inner coil spring 2 to the cylindrical wall 11 of the substrate 1 bystaking.

As shown in FIG. 5C, the end turn portion 2 a of the inner coil spring 2may be narrowed in diameter, and the end turn portion 20 a of the outercoil spring 20 may be also narrowed in diameter to closely approach orcontact the end turn portion 2 a from outside. And, an inner diameter2R3 of the end turn portion 20 a of the outer coil spring 20 may be setsmaller than an outer diameter 2R4 of a second-stage turn 2 c of theinner coil spring 2 (R3<R4). As a result, the outer coil spring 20 isprevented from coming off in the axial direction by the second-stageturn 2 c of the inner coil spring 2 (see FIG. 5D).

In the spring assembly as shown in FIG. 1 where the substrates 1 arearranged at both ends of the coil spring 2, the outer coil spring 20 asshown in FIG. 5A may not come off in the axial direction. However, inthe spring assembly where the substrate 1 is attached only to one end ofthe inner coil spring 2 and the other end thereof is opened, when theouter coil spring 20 is simply arranged outside the inner coil spring 2,the outer coil spring 20 may easily come off. It is therefore necessaryto provide some measure to prevent the outer coil spring 20 from comingoff in the axial direction at the time of factory shipment or the like.

By configuring as shown in FIG. 5C, the outer coil spring 20 isprevented from coming off in the axial direction, without providing aseparate component for coming off prevention.

In a spring assembly as shown in FIG. 6, a convex portion 30 is formedto protrude from the substrate 1 at the outer peripheral side of the endturn portion 20 a of the outer coil spring 20. The convex portion 30 hasan effect of enhancing rigidity of the outer coil spring 20. That is,when an external force acts on the substrate 1 in a horizontal direction(a direction perpendicular to the axis direction), the outer coil spring20 may be deformed while slipping on the surface of the substrate 1. Atthis time, if the convex portion 30 is formed at the outer peripheralside of the end turn portion 20 a of the outer coil spring 20, the endturn portion 20 a is prevented from slipping by the convex portion 30,thereby preventing deformation. As a result, a resistance force againstthe external force is enhanced, and buckle of the outer coil spring 20is prevented.

In an example shown in FIG. 6, the convex portion 30 is formed by theextrusion molding. However, shape (a position, a height and the like)and forming method are not limited thereto. For example, the convexportion 30 is formed by half blanking to the substrate 1, cutting andbending up the substrate 1, or attaching a separate component.

In a spring assembly as shown in FIG. 7, the outer coil spring 20 has adouble-turned structure of an end turn portion 20 a and an end turnportion 20 b. The end turn portions 20 a and 20 b of the outer coilspring 20 are narrowed in diameter to closely approach or contact theend turn portion 2 a of the inner coil spring 2 from outside, therebyfunctioning as a support wall for the inner coil spring 2. By arrangingthe end turn portion 20 b of the outer coil spring 20 outside, the endturn portion 2 a of the inner coil spring 2 is strongly held by the endturn portions 20 a and 20 b, and the radial movement of the end turnportion 2 a is prevented. When a radius R1 of a wire rod forming theouter coil spring 20 is larger than a radius R2 of a wire rod formingthe inner coil spring 2 (R1>R2) as shown in FIG. 5A, the end turnportion 20 b of the outer coil spring 20 prevents the inner coil spring2 from coming off in the axial direction, thereby functioning as thespring fixing wall.

In this case, since the cylindrical wall 11 at the inner peripheral sideof the inner spring coil 2 is not necessary to function as the springfixing wall and only necessary to function as the support wall toprevent the radial movement of the inner coil spring 2, it is notnecessary to fix the inner coil spring 2 to the cylindrical wall 11 ofthe substrate 1 by staking.

[Third Embodiment]

Next, a third embodiment will be described.

In a spring assembly according to the present embodiment, plural coilsprings are coaxially arranged to increase the spring force against thesubstrate, as the second embodiment.

FIGS. 8A and 8B respectively illustrate configurations of the springassembly according to the third embodiment.

As shown in FIG. 8A, an inner coil spring 2 and an outer coil spring 20are coaxially arranged on the substrate 1. The inner coil spring 2arranged at the inner peripheral side of the outer coil spring 20 has anend turn portion 2 a broadened in diameter, and the end turn portion 2 afunctions as a support wall for the outer coil spring 20. That is, bybroadening the end turn portion 2 a of the inner coil spring 2 indiameter, the end turn portion 2 a closely approach or contact the endturn portion 20 a of the outer coil spring 20 from inside. Thus, the endturn portion 20 a of the outer coil spring 20 is prevented from movingin the radial direction by the end turn portion 2 a of the inner coilspring 2.

In addition, in the present embodiment, an outer-side wall 12 of thesubstrate 1 is formed to fix the end turn portion 20 a of the outer coilspring 20 from outside and functions as the spring fixing wallpreventing the outer coil sprint 20 from coming off in the axialdirection.

In the figures, a radius of a wire rod forming the outer coil spring 20is larger than a radius of a wire rod forming the inner coil spring 2.However, the radius of the wire rod forming the inner coil spring 2 maybe set larger than the radius of the wire rod forming the outer coilspring 20. In this case, when being attempted to come off, the end turnportion 20 a of the outer coil spring 20 contacts the end turn portion 2a of the inner coil spring 2 and is prevented from coming off in theaxial direction. That is, the inner coil spring 2 functions as thespring fixing wall. When the inner coil spring 2 functions as the springfixing wall preventing the outer coil spring 20 from coming off, theouter-side wall 12 of the substrate 1 is not necessary to function asthe spring fixing wall and only necessary to function as the supportwall preventing the outer coil spring 20 from moving in the radialdirection. Therefore, it is not necessary to fix the outer coil spring20 to the outer-side wall 1 of the substrate 1 by staking.

As shown in FIG. 8A, the end turn portion 2 a of the inner coil spring 2may be broadened in diameter so that an outer diameter of end turnportion 2 a is larger than an inner diameter of a second-stage turn 20 cof the outer coil spring 20. In this case, the inner coil spring 2 isprevented from coming off in the axial direction by the second-stageturn 20 c of the outer coil spring 20.

In the spring assembly where the substrate 1 is attached only to one endof the outer coil spring 20 and the other end thereof is opened, whenthe inner coil spring 2 is simply arranged inside the outer coil spring20, the inner coil spring 2 may easily come off. It is thereforenecessary to provide some measure to prevent the inner coil spring 2from coming off in the axial direction at the time of factory shipmentor the like.

By configuring as above, the inner coil spring 2 is prevented fromcoming off in the axial direction, without providing a separatecomponent for coming off prevention.

In a spring assembly as shown in FIG. 8B, the inner coil spring 2 has adouble-turned structure of an end turn portion 2 a and an end turnportion 2 b. The end turn portions 2 a and 2 b of the inner coil spring2 are broadened in diameter to closely approach or contact the end turnportion 20 a of the outer coil spring 20 from inside, therebyfunctioning as a support wall for the outer coil spring 20. By arrangingthe end turn portion 2 b of the inner coil spring 2 outside, the endturn portion 20 a of the outer coil spring 20 is strongly held by theend turn portions 2 a and 2 b, and the radial movement of the end turnportion 20 a is prevented.

[Other Configuration Examples]

The present invention is not limited to the above embodiments, and canbe variously modified or applied without departing from the technicalscope of the present invention.

For example, based on the configuration of the second embodiment shownin FIGS. 5A to 5D and FIG. 6, two or more outer coil springs may becoaxially arranged outside the inner coil spring 2. In this case, whilethe end turn portion 2 a of the coil spring 2 is narrowed in diameter,by also narrowing the end turn portions of the outer coil springs indiameter, respectively, so as to interfere with second-stage turns ofthe coil springs located inside, all outer coil springs are respectivelyprevented from coming off in the axial direction.

A spring assembly in which plural coil springs are coaxially arranged toincrease the spring force against the substrate may include a fixed coilspring (fixed/staked to the substrate) and a non-fixed coil spring (notfixed/staked to the substrate). When the substrate is attached only toone ends of the coil springs and the other ends thereof are opened, inorder to prevent the non-fixed coil spring from coming off in the axialdirection, the fixed coil spring and the non-fixed coil spring may beconfigured to interfere with each other by broadening or narrowing adistal end (a free end not fixed to the substrate) of the fixed coilspring in diameter and by narrowing or broadening a proximal end of thenon-fixed coil spring in diameter.

In a spring assembly as shown in FIG. 9A where only one end of the innercoil spring 2 is fixed to the substrate 1 and the other end thereof isopened, if the outer coil spring 20 is simply arranged outside the innercoil spring 2, the outer coil spring 20 may easily come off. It istherefore necessary to provide some measure to prevent the outer coilspring 20 from coming off in the axial direction at the time of factoryshipment or the like.

By broadening the end turn portion 20 a of the outer coil spring 20 indiameter while narrowing the free end 2 d of the inner coil spring 2 indiameter, when the outer coil spring 20 attempts to come off in theaxial direction as indicated by an arrow in the figure, the end turnportion 20 a of the outer coil spring 20 interfere with the free end 2 dof the inner coil spring 2. According to the above configuration, theouter coil spring 20 is prevented from coming off in the axialdirection, without providing a separate component for coming offprevention.

In a spring assembly as shown in FIG. 9B, the inner coil spring 2 has adouble-turned free end of an end turn portion 2 d and an end turnportion 2 e configured to closely approach or contact a free end 20 d ofthe outer coil spring 20, thereby preventing the axial movement of theouter coil spring 20 not fixed to the substrate 1. In this case, anintermediate turn portion of the non-fixed outer coil spring 20 and anintermediate turn portion of the fixed inner coil spring 2 are preventedfrom interfering or becoming tangled with each other, so that thecharacteristics of the coil spring may not fluctuate.

In a spring assembly as shown in FIG. 10A where only one end of theouter coil spring 20 is fixed to the substrate 1 and the other endthereof is opened, if the inner coil spring 2 is simply arranged insidethe outer coil spring 20, the inner coil spring 2 may easily come off.It is therefore necessary to provide some measure to prevent the outercoil spring 20 from coming off in the axial direction at the time offactory shipment or the like.

By broadening the end turn portion 2 a of the inner coil spring 2 indiameter while narrowing the free end 20 d of the outer coil spring 20in diameter, when the inner coil spring 2 attempts to come off in theaxial direction as indicated by an arrow in the figure, the end turnportion 2 a of the inner coil spring 2 interfere with the free end 20 dof the outer coil spring 20. According to the above configuration, theinner coil spring 2 is prevented from coming off in the axial direction,without providing a separate component for coming off prevention.

In a spring assembly as shown in FIG. 10B, the outer coil spring 20 hasa double-turned free end of an end turn portion 20 d and an end turnportion 20 e configured to closely approach or contact a free end 2 d ofthe inner coil spring 2, thereby preventing the axial movement of theinner coil spring 2 not fixed to the substrate 1. In this case, anintermediate turn portion of the non-fixed inner coil spring 2 and anintermediate turn portion of the fixed outer coil spring 20 areprevented from interfering or becoming tangled with each other, so thatthe characteristics of the coil spring may not fluctuate.

FIG. 11A illustrates a state where a free end shown in FIG. 9B isbrought into contact with the counterpart member, and 11B illustrates astate where a free end shown in FIG. 10B is brought into contact withthe counter part member. In the configuration shown in FIG. 11A, whilethe inner coil spring 2 has the double-turned free end (2 d and 2 e),the outer coil spring 20 also has a double-turned free end (20 d and 20e). And, in the configuration shown in FIG. 11B, while the outer coilspring 20 has the double-turned free end (20 d and 20 e), the inner coilspring 2 also has a double-turned free end (20 d and 20 e).

As a result, since the double-turned free end is brought into contactwith the counterpart member, a force may be stably applied to thecounterpart member.

The following configurations are also effective for securely fixing theend turn portion of the coil spring to the substrate.

FIGS. 12A to 12E and FIGS. 13A to 13C illustrate various fixingconfigurations of a coil spring and a substrate. In the configurationsshown in FIGS. 12A to 12E, a spring fixing shaft 100 is arranged toprotrude from the substrate 1, and a holding projection 101 is providedon the spring fixing shaft 100. The holding projection 101 radiallyexpands toward the substrate 1. The holding projection 101 having anumbrella shape may be simply formed on the peripheral surface of theround rod-like spring fixing shaft 100 as shown in FIG. 12A, so as tocatch the end turn portion 2 a of the coil spring 2. The holdingprojection 101 may be spirally formed as shown in FIG. 12B, so as tocatch plural turn portions of the coil spring 2. Moreover, as shown inFIG. 12C and FIG. 12D, a holding projection 201 may be formed on aplate-like spring fixing shaft 200.

Further, as shown in FIG. 12E, a cylindrical spring fixing shaft 300 maybe provided to surround the coil spring 2, and a holding projection 301may inwardly protrude from an inner peripheral surface of the springfixing shaft 300 to catch the coil spring 2.

In the configuration shown in FIG. 13A, the spring fixing shaft 100frictionally contacts the inner peripheral side of the coil spring 2. Ifa setting is provided so that the coil spring 2 is radially expandedwhen the coil spring 2 is screwed toward the proximal end of the springfixing shaft 100, when the coil spring 2 spirally moves toward thedistal end of the spring fixing shaft 100, the coil spring 2 is narrowedin diameter to press-contact the spring fixing shaft 100, and africtional force (retention force) between the spring fixing shaft 100and the coil spring 2 increases, so that the coil spring 2 may not comeoff.

A catching portion may be provided in a proximal end portion of thespring fixing shaft 100 to catch an end portion of the coil spring 2.For example, as shown in FIG. 13B and FIG. 13C, a proximal end portionof the spring fixing shaft 100 is formed into a D- or I-shapedcross-section having a flat catching portion 100 a, and a hookingportion 2 b formed at an end portion of the coil spring 2 is hooked onthe flat catching portion 100 a. Moreover, when the spring fixing shaft100 is formed into a plate shape, the flat surface thereof forms thecatching portion 100 a.

Although the material of the spring fixing shaft 100 is not limited,when the spring fixing shaft 100 is formed from a synthetic resin, thespring fixing shaft 100 may expand due to a high-temperature useenvironment, moisture absorption and swelling caused by adhesion of alubricant oil or the like, thereby increasing an overlapping margin withthe coil spring 2 and further increasing a retention force.

What is claimed is:
 1. A spring assembly comprising: a substrate; a coilspring having an end turn portion fixed to the substrate; an inner wallprovided at an inner peripheral side of the coil spring so as to form athrough hole in the substrate; and an outer wall provided at an outerperipheral side of the coil spring, wherein the inner wall forms aspring fixing wall configured to prevent the end turn portion of thecoil spring from coming off in an axial direction of the coil spring,wherein the outer wall forms a support wall configured to prevent theend turn portion of the coil spring from moving in a radial direction ofthe coil spring, wherein the inner wall extends outward towards theouter wall so as to stake the end turn portion of the coil spring, andwherein a width of an opening formed by the inner wall and outer wall isless than a diameter of a wire rod forming the end turn portion of thecoil spring.
 2. The spring assembly of claim 1, wherein the inner wallextends from the substrate along the inner peripheral side of the coilspring, and wherein the outer wall extends from the substrate along theouter peripheral side of the coil spring.
 3. The spring assembly ofclaim 2, wherein the outer wall forming the support wall is formed byhalf blanking to the substrate.
 4. The spring assembly of claim 2,wherein the outer wall forming the support wall is formed by cutting andbending up the substrate.
 5. The spring assembly of claim 2, wherein theinner wall forming the spring fixing wall is formed as a cylindricalwall extending from the substrate, wherein a distal opening edge of thecylindrical wall is broadened in diameter to stake the end turn portionof the coil spring to the cylindrical wall of the substrate, wherein anextension amount of the spring fixing wall from the substrate is setlarger than a radius of a wire rod forming the coil spring, wherein aninterval between a distal end of the spring fixing wall and a distal endof the support wall after being staked is smaller than a diameter of thewire rod, and wherein a gap is formed between the outer wall forming thesupport wall and the end turn portion of the coil spring.
 6. The springassembly of claim 2, wherein the inner wall forming the spring fixingwall is formed as a cylindrical wall extending from the substrate,wherein a distal opening edge of the cylindrical wall is broadened indiameter to stake the end turn portion of the coil spring to thecylindrical wall of the substrate, and wherein the outer wall formingthe support wall is in contact with the end turn portion of the coilspring.
 7. The spring assembly of claim 1, wherein the outer wall isformed in the substrate such that a side of the substrate opposite thecoil spring extends toward the coil spring at a portion of the substrateon which the outer wall is formed.
 8. The spring assembly of claim 1,wherein a side of the outer wall opposite the coil spring comprises astep portion.
 9. The spring assembly of claim 1, wherein a bottom of thesubstrate includes an indented portion under the outer wall.
 10. Thespring assembly of claim 1, wherein a height of the outer wall isgreater than a radius of a wire rod forming the coil spring.
 11. Thespring assembly of claim 1, wherein a gap is formed between the end turnportion of the coil spring and the outer wall.
 12. A method formanufacturing a spring assembly the method comprising: providing a coilspring; providing a substrate, the substrate including: an inner wallprovided at an inner peripheral side of the coil so as to form a throughhole in the substrate; and an outer wall provided at an outer peripheralside of the coil spring; coaxially arranging the end turn portion of thecoil spring to the inner wall of the substrate; and broadening thedistal opening edge of the inner wall in diameter to form the the innerwall into a spring fixing wall while bringing the end turn portion ofthe coil spring into contact with the outer wall forming a support wall,wherein the spring fixing wall is configured so as to prevent the endturn portion of the coil spring from coming off in an axial direction ofthe coil spring, wherein the outer wall forming the support wallprevents the end turn portion of the coil spring from moving in a radialdirection of the coil spring, wherein the inner wall extends outwardtowards the outer wall so as to stake the end turn portion of the coilspring, wherein the inner wall forming the spring fixing wall extendsfrom substrate along the inner peripheral side of the coil spring,wherein the outer wall extends from the substrate along the outerperipheral side of the coil wring, wherein the inner wall forming thespring fixing wall is formed as a cylindrical wall extending from thesubstrate, wherein a distal opening edge of the cylindrical wall isbroadened in diameter to stake the end turn portion of the coil springto the cylindrical wall of the substrate, and wherein the outer wallforming the support wall is in contact with the end turn portion of thecoil spring.
 13. A spring assembly comprising: a substrate comprising ametal; a coil spring having an end turn portion fixed to the substrate;an inner wall provided at an inner peripheral side of the coil spring;and an outer wall provided at an outer peripheral side of the coilspring, wherein the inner wall forms a spring fixing wall configured toprevent the end turn portion of the coil spring from coming off in anaxial direction of the coil spring, wherein the outer wall forms asupport wall configured to prevent the end turn portion of the coilspring from moving in a radial direction of the coil spring, wherein theinner wall extends outward towards the outer wall so as to stake the endturn portion of the coil spring, and wherein a width of an openingformed by the inner wall and outer wall is less than a diameter of awire rod forming the end turn portion of the coil swing.